"The surface of this sea must be very nearly two hundred miles (if not more) below the level of the moon's exterior; all the cities of the moon lie, I learnt, immediately above this Central Sea, in such cavernous spaces and artificial galleries as I have described, and they communicate with the exterior by enormous vertical shafts which open invariably in what are called by earthly astronomers the 'craters' of the moon. The lid covering one such aperture I had already seen during the wanderings that had preceded my capture.
"Upon the condition of the less central portion of the moon I have not yet arrived at very precise knowledge. There is an enormous system of caverns in which the mooncalves shelter during the night; and there are abattoirs and the like - in one of these it was that I and Bedford fought with the Selenite butchers - and I have since seen balloons laden with meat descending out of the upper dark. I have as yet scarcely learnt as much of these things as a Zulu in London would learn about the British corn supplies in the same time. It is clear, however, that these vertical shafts and the vegetation of the surface must play an essential role in ventilating and keeping fresh the atmosphere of the moon. At one time, and particularly on my first emergence from my prison, there was certainly a cold wind blowing down the shaft, and later there was a kind of sirocco upward that corresponded with my fever. For at the end of about three weeks I fell ill of an indefinable sort of fever, and in spite of sleep and the quinine tabloids that very fortunately I had brought in my pocket, I remained ill and fretting miserably, almost to the time when I was taken into the presence of the Grand Lunar, who is Master of the Moon.
"I will not dilate on the wretchedness of my condition," he remarks, " during those days of ill-health." And he goes on with great amplitude with details I omit here. "My temperature," he concludes, "kept abnormally high for a long time, and I lost all desire for food. I had stagnant waking intervals, and sleep tormented by dreams, and at one phase I was, I remember, so weak as to be earth-sick and almost hysterical. I longed almost intolerably for colour to break the everlasting blue..."
He reverts again presently to the topic of this sponge caught lunar atmosphere. I am told by astronomers and physicists that all he tells is in absolute accordance with what was already known of the moon's condition. Had earthly astronomers had the courage and imagination to push home a bold induction, says Mr. Wendigee, they might have foretold almost everything that Cavor has to say of the general structure of the moon. They know now pretty certainly that moon and earth are not so much satellite and primary as smaller and greater sisters, made out of one mass, and consequently made of the same material. And since the density of the moon is only three-fifths that of the earth, there can be nothing for it but that she is hollowed out by a great system of caverns. There was no necessity, said Sir Jabez Flap, F.R.S., that most entertaining exponent of the facetious side of the stars, that we should ever have gone to the moon to find out such easy inferences, and points the pun with an allusion to Gruyere, but he certainly might have announced his knowledge of the hollowness of the moon before. And if the moon is hollow, then the apparent absence of air and water is, of course, quite easily explained.
The sea lies within at the bottom of the caverns, and the air travels through the great sponge of galleries, in accordance with simple physical laws. The caverns of the moon, on the whole, are very windy places. As the sunlight comes round the moon the air in the outer galleries on that side is heated, its pressure increases, some flows out on the exterior and mingles with the evaporating air of the craters (where the plants remove its carbonic acid), while the greater portion flows round through the galleries to replace the shrinking air of the cooling side that the sunlight has left. There is, therefore, a constant eastward breeze in the air of the outer galleries, and an upflow during the lunar day up the shafts, complicated, of course, very greatly by the varying shape of the galleries, and the ingenious contrivances of the Selenite mind. ...
